1. Field of the Invention
This invention relates to protective headgear. It relates more specifically to a headgear securement system for effectively fitting headgear such as a helmet to a wearer's head.
2. Background Information
Protective headgear such as a helmet is used widely in games and other physical activities to help protect the wearer from head injury. Head injury can result from impact forces due to contact with other people or with objects. Currently marketed helmets generally fall into one of two categories, i.e. single impact helmets or multiple impact helmets. Single impact helmets undergo permanent deformation under impact, whereas multiple impact helmets are capable of withstanding multiple blows. The wearers of single impact helmets include, for example, bicyclists and motorcyclists. On the other hand, participants in sports such as hockey and football generally wear multiple impact helmets. Both categories of helmets have similar constructions which include a semi-rigid outer shell which distributes the force of an impact over a wide area, a crushable layer inside the shell which reduces the force of the impact on the wearer's head and usually also an inner liner that helps to shape the helmet to the wearer's head.
Nearly all helmets provide some sort of device for securing the helmet to the wearer's head. Many of these devices involve a chinstrap assembly designed to retain the helmet on the user's head and to protect the user's chin from the force of an impact. Typically such chinstrap assemblies include a chin protector and an adjustable chinstrap which connects the chin protector to the helmet at opposite sides of the helmet's face opening. The length of the chinstrap may be adjusted to draw down and seat the helmet on the user's head and to place the chin protector against the chin. In other words, the strap assembly simply adjusts the distance between the chin protector and the helmet.
Thus, the prior chinstrap assemblies do nothing to affect the helmet in any way so that it more closely conforms to the shape of the wearer's head. No attempt is made to use the chinstrap assembly as a means to alter the helmet to achieve an optimal fit for a particular wearer. This is most likely due to the fact that most conventional helmets are not particularly accommodating to a variety of different head shapes and sizes.
However, there has already been developed by me a class of protective headgear incorporating a plurality of energy-absorbing layers. Such headgear is disclosed, for example, in publications WO 2006/089234 and WO 2006/089235. As seen there, these helmets include a semi-rigid outer layer or shell, an inner layer and a middle layer between the outer and inner layers. This middle layer is composed of a plurality of individual compressible cells disposed in a fluid-containing interstitial region formed by the inner and outer layers. At least one passageway is provided by which fluid in the interstitial region and fluid expelled from the cells can leave the middle layer as the outer layer deforms in response to an impact on the helmet.
Preferably, such helmets also include a compressible inner liner whose shape can change to conform to a wearer's head as each helmet is drawn down on the head by an associated chinstrap assembly which includes a chin protector and adjustable chinstraps. Such an arrangement is described in publication WO 2006/089098. As seen there, the straps extending from the chin protector are still connected to corresponding locations at the opposite sides of the helmet outer layer or shell. Therefore, the tightening of the chinstrap has no effect on the physical characteristics of the helmet per se.